Thermocouples have long been used to measure temperatures within reactors or other vessels, such as may be used in the petrochemical industry. Examples of such thermocouple measuring devices are illustrated by U.S. Pat. Nos. 3,262,502 and 3,637,438. Thermocouple assemblies of such type comprise a number of thermocouple leads and junctions, usually encapsulated in a sheath which are inserted either directly within such a reactor or vessel, or inserted within a well which well is positioned within the vessel. The thermocouple leads exit the vessel or well to a junction box which contains electrical terminals, from which known instrumentation provides a temperature reading adjacent the diversely positioned thermocouple junctions. For safety reasons, it is desirable to pressure seal or insulate the interior of the reactor or vessel as to prevent pressure escape in the area where the thermocouple leads exit the vessel. An approach previously used has been to utilize compression fittings for the sheathed thermocouples. Such an approach has required excessive clearance around each fitting for wrench engagement. A more recent development utilizes multi-holed plates. Sheathed thermocouples are passed through such holes and are brazed to the plate. Such arrangement resulting in heating the entire plate in order to braze a single sheath. This is extremely delicate work and may result in damaging adjacent sheath-plate junctions when affixing or repairing a single sheath. It was to overcome these problems associated such multi-holed plates that this invention was developed.